99 



PsAMMOBiA LUSORiA. — Shell transversely, oblong-subovalj 

 oluish-whitc, witli minute transverse wrinkles ; apex rather nearer 

 the anterior end ; anterior margin narrowed, inclining to the left 

 at the end and gaping ; cartilage slope rectilinear, with an obtuse, 

 obsolete, convex line on the left valve. 



Length three-fifths of an inch. Breadth one inch. Inhabits the 

 Southern States. Cabinet of the Academy and Philadelphia Mu- 

 seum. 



This shell does not appear to be very common. It seems to 

 vary in having often two teeth on each valve, as in Sanguinolaria. 



DoNAX VARIABILIS. — Shell triangular; anterior margin ob- 

 liquely truncated, cordate, suture a little convex ; posterior hinge 

 margin nearly rectilinear, suture indented ; base a little prominent, 

 beyond a regular cui-ve, near the middle ; valves longitudinally 

 striated with numerous, equal, parallel, regular, impressed lines, 

 hardly visible to the unassisted eye, and obsolete on the posterior 

 margin ; basal edge within crenate. 



Length half an inch. Width nine-tenths of an inch. Thick- 

 ness seven-twentieths of an inch. Inhabits the coast of Georgia 

 and East Florida. Cabinet of the Academy and Philadelphia Mu- 

 seum. 



Varies very much in color and is a very pretty shell. Its usual 

 varieties are red, white, yellow, or elegantly radiated with dilated 

 reddish-brown lines, upon a white or yellow ground ; lines are pur- 

 purescent within the shell. A veiy common shell ; I found it 

 more particularly numerous on the beach of Cumberland island, 

 where, in favorable situations, at the recess of the tide, it may be 

 taken up in handfuls, without any intermixture of sand. It is 

 very distinct from D. rugosa, but approaches much nearer to D. 

 trunculus, from which it is distinguished by being more abruptly 

 truncated before, smaller, and the longitudinal lines are more in- 

 dented. I have no doubt but this species has been regarded, by 

 authors, as the same with trunculus, if so, judging by an individual 

 of that species in the collection of the Academy, at least two dis- 

 tinct species have been confounded together under that common 

 name. 



DoNAX POSSOR. — Shell subtriangular ; anterior margin short and 

 rounded ; posterior hinge slope rectilinear ; base very slightly 

 prominent beyond a regular curve at the middle; valves longitudi- 



